There is an obvious gap between China and developed countries in the weldability research of steel and welding materials. In recent years, a lot of detailed research works have been done on weldability of several domestic high-end steels and welding materials for pressure vessels. That is, making steel from the point of view of welding, to make the steel from ‘weldable’ to ‘easry to welding’. Through reasonably selecting the welding slag system and optimizing the alloy system and formula, the welding materials have good performance. A good match between welding material and steel is realized, the welding joint has low crack sensitivity, low welding heat input sensitivity, good crack arrest performance and good low temperature impact toughness, which provides a strong guarantee for the welding quality of pressure vessels.